Objective: The purpose of this study was to report improvement in patients with autism spectrum disorder (ASD) treated with herbal medication described in Shanghanlun.

Methods: The patient was diagnosed with Lesser Yin disease based on the 315th provision of Shanghanlun, and Baektonggajeodamjup-tang was used for treatment. The result was evaluated using the Korean-Childhood Autism Rating Scale (K-CARS).

Results: The K-CARS score decreased from 32 to 15 after 7 months of treatment.

Conclusions: Lesser Yin disease 315th provision of Shanghanlun may be a provision describing ASD; in addition, Baektonggajeodamjup-tang may be an effective treatment for ASD.

Keywords: Shanghanlun, Soyinbing, Baektonggajeodamjup-tang, Autism spectrum disorder (ASD), disease pattern identification diagnostic system based on Shanghanlun provisions (DPIDS), Herbal medicine